JP2003527240A - Method for producing activated carbon fiber-producing filter member and protective garment obtained by the method - Google Patents

Abstract

(57) Summary The present invention relates to a method comprising the following steps (1) and (2): (1) By using a manufacturing method such as knitting, stitching or braiding of a two-dimensional woven fabric, the method comprises the steps of: Producing a preform of the product to be produced from the carbon precursor fiber woven fabric, and (2) carbonizing and activating the preform in order to directly obtain an activated carbon fiber product having a desired form. (Where the dimensions of the preform are determined in view of carbonization and shrinkage during the activation process). This method is particularly suitable for the manufacture of clothing to protect against nuclear, biological or scientific attacks.

Description

Detailed Description of the Invention

TECHNICAL FIELD This invention relates to manufacturing shaped filter members having adsorptive properties using activated carbon fibers. As used here, "shaped filter member (shaped filte
The term "r pieces" means a self-supporting filter member having a non-planar morphology. This invention is particularly applicable to shaped clothing, such as gloves, used to protect civilians or military personnel from attacks resulting from nuclear, biological or chemical causes.
Specially concerned with manufacturing socks, underwear and hats. However, the method according to the invention can also be used in other applications, for example in the manufacture of filter elements having special configurations, for example sleeve-like configurations, spherical cap configurations and the like.

BACKGROUND ART Various materials have been proposed for manufacturing protective clothing against nuclear, biological and chemical weapons (NBC). For example, it is known to produce protective suits made of thick rubber (generally isobutyl rubber). This type of suit is particularly uncomfortable and unbearable when the temperature is relatively high, because it holds breath air.

It has also been proposed to use activated carbon particles dispersed in a foam, eg polyurethane foam. The suits or garments produced by this method are not only bulky, but also have the drawbacks of being difficult to wash due to the presence of the foam and being sluggish in the event of a fire. In addition, porosity and breathability are affected when the shaped support needs to be laminated for use. In addition, for example, under humid conditions caused by perspiration, the adsorptivity of activated carbon decreases.

It has also been proposed to use activated carbon fibers. The mechanical properties of activated carbon fibers make them difficult to undergo texturing operations (eg, spinning, weaving, knitting, sewing and braiding, etc.) to produce shaped articles of clothing. Activated carbon fibers can be incorporated onto a support in the form of a garment to be manufactured, but the aforementioned drawbacks of blocking the pores and reducing breathability are problematic.

To solve the problem posed by carbon fibers that is unsuitable for tissue manipulation, a core (eg, a metal core) having the necessary mechanical properties and wrapping or wrapping the core. There is also proposed a method of using a composite yarn containing the above carbon precursor fiber (see French Patent Document FR25997661A). This composite yarn can be used in the manufacture of cloth prior to carbonization and activation treatment of carbon precursor fibers. According to French patent document FR 2 599 761 A, the cloth obtained can be used for the production of protective clothing. The drawbacks of this method are the complexity and the high cost of manufacturing the composite yarn. Another disadvantage is the presence in the resulting garment of metal reinforcements that make the garment very rigid, which is a disadvantage from a military application point of view.

Activated carbon cloth is known and is used in filter element applications. A method for manufacturing this type of cloth is described in French patent document FR2741363A and in international patent publication WO 989 / 41678A. However, a sewing operation is necessary in order to manufacture a shaped article of clothing from the cloth. In addition, the stitches formed in the carbon cloth locally increase the rigidity significantly, resulting in increased discomfort. In addition, the stitches allow the toxins to be retained to pass easily by making the pore sizes non-uniform.

(Disclosure of the Invention) (Technical Problems to be Solved by the Invention) The technical problems to be solved by the present invention include the molding filter member and the above-mentioned drawbacks, although not particularly limited thereto. It is an object of the present invention to provide a method of manufacturing an NBC protective clothing article.

More particularly, the present invention is a shaped filter member integrally manufactured from activated carbon fiber, which is washable, thermally stable and has good adsorption properties under humid conditions. It is an object of the invention to obtain a shaped filter member which retains the above properties and inherently exhibits good mechanical strength, and which also provides pores free of preferred passages for the medium to be filtered.

(Solution Method) Such an object was achieved by a method including the following steps (1) and (2): (1) Carbon precursor fiber agglomeration by using a textile manufacturing method A preform of the product to be manufactured consisting of a functional textile, and then (2) carbonizing and activating treatment to directly obtain a shaped article of the activated carbon fiber having the desired morphology (this In this case, the dimensions of the preform are determined by taking into account the carbonization and shrinkage during the activation process).

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is notable in the following points. That is, after the carbon precursor fiber preform, which has been pre-processed by the textile method and has a shape corresponding to the shape of the manufactured article, is subjected to carbonization and activation treatment, the filter member is directly Can be obtained.

At least a portion of the weaving method used to shape the preform can be knitted, sewn or braided into a two-dimensional weave. As used herein, the term "two-dimensional fabric" means a woven or multidirectional web.

The preform is produced as a cellulose fiber woven fabric using, for example, rayon fibers, whereby high-purity carbon fibers can be obtained, and a large specific surface area, for example, 800 m ² / g or more, or 1200 m A specific surface area of ² / g or more can be achieved.

In a first embodiment of the invention, the carbonization and activation treatment comprises the following steps (1) and (2): (1) heat treatment at 250-500 ° C. under an inert atmosphere. Carbonization step, and (2) carbonization preform activation step performed at 750 to 950 ° C. Activation is carried out in an oxidizing atmosphere, such as an atmosphere of steam and / or carbon dioxide.

In the second embodiment of the present invention, the carbon and the activation step include the following steps (1) and (2): (1) A composition containing at least one component having a cellulose decomposition accelerating ability. Of impregnating a preform with a product, and (2) 350 to 500 ° C. for directly obtaining a filter member made of activated carbon fiber
Heat treatment process in.

The present invention also provides an article of clothing obtainable by the above method, that is, a shaped article of clothing manufactured as a single piece of a coherent woven fabric composed of activated carbon fibers.

It should be noted that this type of garment inherently exhibits the strength required to be used, although it is manufactured from activated carbon fibers. Furthermore, since this type of clothing is made of carbon, the clothing according to the invention exhibits good properties and is thermally stable even in the presence of fire. Carbon fibers also eliminate static electricity due to their conductivity. Also, they can be easily washed. As compared with activated carbon particles, the performance deterioration of the product made of activated carbon fiber due to moisture is significantly suppressed. The majority of pores in activated carbon fibers are micropores that are unsuitable for being filled with water by capillary action. Furthermore, because of their very small size compared to activated carbon particles, activated carbon fibers exhibit a very large external surface area to the gas stream for a given amount of carbon. The thickness of this type of product required to obtain a given performance can be significantly reduced.

The present invention is better understood by the following non-limiting description based on the accompanying figures. FIG. 1 illustrates successive steps in a method that constitutes one embodiment of the present invention. FIG. 2 shows successive steps in a method which constitutes a variant of the embodiment shown in FIG. FIG. 3 is a photograph showing a glove preform knitted using viscose yarn and an activated carbon glove obtained by subjecting the preform to carbonization and activation treatment.

The following description relates to the manufacture of protective clothing. As mentioned above, the present invention is not limited to such applications and more generally encompasses the manufacture of shaped filter members.

The first step (10) of the method shown in FIG. 1 is by using a textile manufacturing method,
This includes manufacturing a preform for the article to be manufactured. Preforms are made with carbon precursors in the form of yarn or spun yarn. Various types of precursors, such as preoxidized polyacrylonitrile (PAN),
Pitch and phenolic compounds can be used. Preference is given to using cellulose precursors, in particular viscose, for example rayon.

The preform is shaped so as to have a shape corresponding to the shape of the article to be manufactured. In this case, modeling is performed in consideration of shrinkage that occurs during carbonization and activation treatment. This shaping can be carried out directly using knitted or braided yarns of carbon precursor fibers or spun yarns.

In addition, a two-dimensional woven fabric, for example, a woven fabric or a multi-directional web is first produced from a yarn or spun yarn of carbon precursor fiber, the woven fabric is cut, and then sewn using the same type of yarn or the like. It is also possible to form a preform by doing. Multidirectional webs are produced by superimposing a plurality of unidirectional webs of yarns or spun yarns oriented parallel to a given direction. Unidirectional webs can be superimposed in different directions and can be, for example, sutured or lightly needled if desired.
ng) or the like to bond them to each other.

The second step (20) of the foregoing method involves carbonizing the preform. Carbonization involves a heat treatment step in an inert atmosphere at 250-500 ° C, for example about 400 ° C. This heat treatment step involves a low heating rate (generally 0.01 ° C / min to 0.5 ° C).
/ Minute) for a relatively long time (several days to several weeks). Then, the final stage of the heat treatment is carried out under an inert atmosphere at a higher temperature, for example, 600 to 900 ° C. for a very short time (for example, several minutes).

Additional heat treatment may be performed to facilitate removal of impurities associated with the gaseous effluent.
Under reduced pressure (for example, 5 to 60 Pascal (Pa)), higher temperature (for example, 1000 to 1)
It may be carried out at 300 ° C. for a relatively short time (about 1 minute).

The aforementioned third step (30) involves activation of the resulting carbon fiber preform. This activation is carried out by subjecting the carbon fiber preform to a heat treatment in an oxidizing atmosphere (eg steam or preferably carbon dioxide or a mixture of carbon dioxide and steam). In this regard, please refer to the above-mentioned French patent document FR2741363A. The heat treatment temperature and the treatment time are functions of the desired specific surface area, and the treatment temperature is 750 to 950 degrees (preferably 850 to 950 ° C).
And the treatment time is preferably 5 to 300 minutes. This gives 800
A product made of activated carbon fiber having a specific surface area of m ² / g or more or 1200 m ² / g or more can be obtained.

The final step (40) of post-treatment may optionally be performed as a function of product application. For example, the post-treatment may include treatment to form very fine deposits, which may cause the carbon particles to stick and prevent the carbon particles from detaching during use of the product. This deposition can be done by spraying with an elastomer or latex.

Another post-treatment may include providing the product with a lining. The lining does not give strength to the product and has the function of avoiding direct contact between the product and the skin of the user. This lining may be breathable, which avoids adverse effects on the porosity and permeability of the product. In this case, it is necessary to bond the product and the lining, for example, using an adhesive only at a few points.

FIG. 2 illustrates a variation of a method suitable for using a cellulose precursor fiber preform. This modification differs from the method shown in FIG. 1 in the following points. That is, in the carbonization step (20) and the activation step (30), the step (20 ′) of impregnating the composition containing the component for promoting dehydration of cellulose into the preform and the step of directly activating the activated carbon fiber product Respectively by the heat treatment step (30 ') for obtaining the desired value.

The impregnation treatment is a composition containing at least one component that promotes dehydration of cellulose, for example, an inorganic component selected from phosphoric acid, zinc chloride, potassium sulfate, potassium hydroxide, diammonium phosphate and ammonium chloride. It is done using things. The impregnation treatment is preferably performed using a phosphoric acid-containing composition, and the amount of phosphoric acid fixed on the preform is 10 to 22 relative to the weight of the dry preform.
% By weight. The heat treatment is performed by heating to a predetermined temperature (350 to 500 ° C.) at a temperature rising rate of 1 to 15 ° C./min in an atmosphere containing a reaction activator such as carbon dioxide or water vapor or in an inert atmosphere. The product obtained is then preferably subjected to a washing treatment. A method of this kind is described in the international patent application WO98 mentioned above.
/ 41678. In this way, a product made of activated carbon fiber is obtained directly.

Example 1 A preform of a glove of the type shown on the left side of the photograph in FIG. 3 was produced by knitting a 330 dtex rayon yarn by knitting a stocking. The edging of the glove was formed using 167 dtex rayon yarn. The preform was placed on the frame in the furnace and subjected to heat treatment for about 2 weeks. About 4
The rate of temperature rise until reaching 00 ° C was very slow (0.1 ° C / min). The resulting preform was then subjected to a heat treatment at about 700 ° C. for about 15 minutes to stabilize the carbon lattice. The carbonized preform was placed in a rotary autoclave in which carbon dioxide (CO ₂ )
It was subjected to activation treatment in an atmosphere at about 850 ° C. for about 1 hour (h).

A glove as shown on the right side of the photograph in FIG. 3 was obtained. The gloves exhibited the following average properties. Specific surface area: 1500 m ² / g Tensile strength at break: 1.5 decanewton (daN) / cm Elongation at break: about 50% Carbon content: about 95% Diameter of activated carbon fiber (filament): about 17 μm

The shrinkage caused by carbonization and activation averaged 32%. This shrinkage must be considered in order to produce a preform that yields a glove of the desired size. It will be appreciated that, depending on the textile product used and the morphology of the product, the shrinkage need not be uniform in all directions throughout the product. The morphology to be imparted to the preform is preferably determined by a test that can mimic the model to be manufactured.

To avoid direct contact with the user's skin, activated carbon fiber gloves can be worn, for example, on cotton underglove. The bottom glove and the glove can be joined by several glue spots. The joint product obtained can be directly inserted into, for example, leather upper gloves. During operation, only the joint formed by the activated carbon fiber glove and the lower glove is consumed. The bonded article can be easily incinerated without producing toxic waste.

Example 2 A glove preform as produced in Example 1 was treated with 20% phosphoric acid (H ₃ PO ₄ ).
The preform was impregnated with phosphoric acid by immersion in a volume% aqueous solution. By subjecting the impregnated preform to a heat treatment at 70 to 90 ° C., water and phosphoric acid adhering to the preform, which accounted for about 16% by weight with respect to the weight of the dry preform, were evaporated. Next, the preform was moved in the heat treatment furnace while being placed on, for example, a glass fiber belt. The heat treatment includes heating the preform to about 200 ° C. at a heating rate of about 5 ° C./min. The heat treatment was performed for 90 minutes in total in an inert atmosphere (nitrogen gas). The resulting gloves were washed in deionized water at about 90 ° C.

The activated carbon fiber gloves produced in this way have the following properties: Specific surface area: about 800 m ² / g Tensile breaking strength: about 1.2 daN / cm Breaking elongation: about 80% Carbon content : Approximately 80% The average shrinkage measured was 28%.

Test The effectiveness test against mustard gas was carried out using the glove obtained in Example 1. The vapor phase test was performed at 37 ° C. using mustard gas. After more than 8 hours, the mustard gas did not pass through the protective barrier constituted by the gloves.

The liquid phase test was carried out at ambient temperature (20 ° C.) using mustard gas. The mustard gas was contacted with the glove in the form of drops. The amount of mustard gas contamination is
The surface area of the glove was 10 g per 1 m ² . The amount of mustard gas that passed through the glove was measured by extracting an air flow from the inside of the glove at a flow rate of 0.2 × 10 ⁻² m / sec. After 24 hours, the measured amount of the mustard gas passed is 0.2 to
It was 1.02 μg / m ² . These tests show that a very effective protective effect was exerted due to the adsorption properties of the activated carbon fibers.

[Brief description of drawings]

FIG. 1 is a continuous flow chart of a method of making one embodiment of the present invention.

2 is a continuous process diagram in a method of constructing a variation of the embodiment shown in FIG. 1. FIG.

FIG. 3 is a photograph of a glove preform knitted using viscose yarn and an activated carbon glove obtained by subjecting the preform to carbonization and activation treatment.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) A41D 31/00 502 A41D 31/00 502B 502C 503 503N D01F 9/16 521 D01F 9/16 521 D03D 1/00 D03D 1/00 Z 15/00 15/00 A D04B 1/16 D04B 1/16 1/28 1/28 F term (reference) 3B011 AA01 AB01 AC04 4D019 AA01 BA03 BB02 CB06 4L002 AA05 DA01 DA03 EA00 EA04 FA02 FA04 FA06 4L037 AT13 CS06 FA06 FA12 FA15 FA16 PA52 PC10 UA15 UA18 4L048 AA13 DA01 DA22 DA24 EB00 EB05

Claims (12)

[Claims] 1. A method for producing a shaped filter member containing activated carbon fiber, which comprises the following steps (1) and (2): (1) A carbon precursor by using a textile production method. A preform of the shaped filter member made of a fibrous cohesive woven fabric is manufactured, and then (2) carbonization and activation treatment are performed to directly obtain a shaped filter member having a desired shape made of activated carbon fiber. (In this case, the dimensions of the preform are determined taking into account carbonization and shrinkage during the activation process). 2. The method of claim 1, wherein at least a portion of the preform is made by knitting carbon precursor fiber yarns. 3. The method of claim 1, wherein at least a portion of the preform is made by stitching a two-dimensional carbon precursor fiber fabric. 4. The method of claim 1, wherein at least a portion of the preform is made by braiding carbon precursor fiber yarns. 5. The method according to claim 1, wherein the preform is manufactured from a cohesive cellulosic fiber fabric. 6. The method of claim 5, wherein the preform is made from a cohesive rayon fiber fabric. 7. The method according to any one of claims 1 to 6, wherein the carbonization and activation treatment includes the following steps (1) and (2): (1) 250 in an inert atmosphere A carbonization step including heat treatment performed at ˜500 ° C., and (2) an activation step of the carbonized preform performed at 750˜950 ° C. 8. The method according to claim 5 or 6, wherein the carbonization and activation treatments include the following steps (1) and (2): (1) At least one component having a cellulose decomposition accelerating ability. Impregnating the preform with the seed-containing composition, and (2) 350-500 ° C. to directly obtain the activated carbon fiber filter member
The heat treatment process performed in. 9. A shaped protective clothing article comprising activated carbon fibers, characterized in that it is manufactured as a single piece of activated carbon fiber cohesive fabric. 10. The article of clothing according to claim 9, wherein at least a part of the article of clothing is constituted by a knitted fabric of threads made of activated carbon fibers. 11. The article of clothing according to claim 9, wherein at least a part of the article of clothing is made of a two-dimensional carbon fiber fabric woven by stitching. 12. The article of clothing according to claim 9, wherein at least a part of the article of clothing is composed of a braid of threads composed of activated carbon fibers.